Orakzai is one of the tribal regions along the Afghan border where the Pakistani Army has tried to root out militants with offensives against their strongholds.

The strike came a day after a local newspaper reported that Pakistan will launch an offensive in North Waziristan, a known sanctuary for Al-Qaeda and Taliban militants also located in Pakistan's tribal belt.

"We had information that militants gathered there and were planning attacks so we launched the attack," senior government official Zaman Khan told Reuters in Kalaya, the main town of Orakzai. He said six militants were also wounded in the strike.

Pakistan's performance in fighting militancy has come under scrutiny again after it was discovered that Al-Qaeda chief Osama bin Laden had been living in the country.

Army operations have failed to break the back of militant groups such as the Pakistani Taliban, who have stepped up suicide bombings since U.S. special forces killed bin Laden near Islamabad on May 2.

After the bin Laden raid, the United States has told Pakistan it needs to step up the fight against militants.